Apparatus for the storage of fluorine



INVENTORS Homer F. Priest Ariafld V. Greene 2Q, 11%? H. F. PREEET ETALAPPARATUS FOR THE STORAGE OF FLUORINE Filad Jan. 22,

Patented Apr. 29, 1947 APPARATUS FOR THE STORAGE OF FLU ORINE Homer F.Priest, New York, and

Aristid V. Grosse,

Bronxville, N. Y., assignors to the Government of the United States, asrepresented by the Ofiice of Scientific Research and Development, Oflicefor Emergency Management Application January 22, 1943, Serial No.473,249

This invention relates to the improvements in apparatus for the storageof-elementary fluorine and more specifically to aftank for the storageof fluorin under pressure.

The usual practice has been to set up an electrolysis cell at the placewhere it has been desired to produce and utilize the fluorine. Theinstallation and operation of such an apparatus involves considerableexpense, takes up a rather large amount of space, and the handlingthereof is diflicult due to the extremely reactive and poisonous natureof fluorine.

One object of our present invention is to provide a receptacle whichupon introduction of fluorine forms a protective coating which isunreactive with fluorine, so that fluorine can be safely handled andstored under pressure. Another object is to provide a container whichcan be easily transported from place to place and used at differentplaces whenever desired. Other objects will be apparent to those skilledin the art.

The extreme activity of the fluorine gas, its ability to react on theelements to form fluorine compounds, and particularly its ability todecompose almost all compounds, have prevented the development of asuitable means for the storage thereof. The present invention hasovercome such dimculty in providing an apparatus in which it may beindefinitely stored without reaction of the fluorine with the materialof which the apparatus is composed.

It is essential to the invention not only that the tank be made ofcopper, nickel, or a coppernickel alloy with a copper content above 60percent, or some other compound equally eflective to form protectivecoatings preventing decomposition and destruction of the container andthe wasting of the fluorine, but that all sealing compounds be made ofsimilar materials.

The single figure drawing is a semi-diagrammatic view, in sectionalelevation, of the fluorine storage receptacle in its simplest form.

Referring to the drawing, there is shown a cylindrical tank I which haswall 2, with bottom 4 and head 3 both hermetically sealed, welded, orotherwise tightly secured, over the ends of the cylinder, as indicatedat 5 and 6. The tank, as well as all parts and seals as above stated,must be made of a material which forms the protective coating andprevents further reaction of fluorine with the containing surface of thetank.

The threads 8 of seat 9 are threaded into neck 10 which is soldered orwelded to head 3. To insure proper sealing of the valve, the end ll ofseat 9 compresses copper gasket I 2 which rests against collar l3 ofhead 3. Seat 9 may be soldered to neck I 0 to be sure of a proper seal.The plunger l4, diaphragm l5 and nozzle I6, as well as all other partsof the valve must be made of copper, nickel, an alloy of copper withcopper content in excess of 60 percent, or some other material which isnot appreciably corroded or decomposed by the fluorine. The nozzle I6 isfitted to connect to any source where fluorine is being prepared.

Flourine gas is admitted to the evacuated copper cylinder through nozzle"5 of valve I from any source of supply, either directly or through abufier system. If a buifer system is used, it may be set up so that thefluorine generator is connected to a copper dry ice trap and a liquidnitrogen trap where the gas is condensed in the presence of helium toprevent condensation of air in the liquid nitrogen. In such case, theliquid fluorine is evaporated in the copper cylinder from the coppertrap which would be connected to the nozzle.

After the fluorine is transferred to the evacuated copper cylinder I,there may be a slight decrease in the initial pressure of the fluorinedue to reaction with the copper walls of the cylinder. However, after ashort time, there is no further decrease indicating that a protectivecoating of copper fluoride has formed on the subjacent interior surfaceof the copper tank which is immune to further action of fluorine andpreventsany further reaction of the fluorine with the walls of the tank.

Pressures on copper cylinders up to 200 lbs, per square inch have beenused. Nickel tanks have likewise proved equally effective for equivalentpressures. Storage at greater pressures has been achieved by reenforcingthe copper or nickel cylinders in steel casings. Steel cylinders linedwith copper or nickel can also be used for storage under high pressure.

Whereas a nickel diaphragm valvehas been mentioned, it is not intendedto limit the invention to that particular type of valve, but any copper,nickel, or copper alloy valve suitable for the purpose may be used. Anyworkable system of passing the fluorine to the tank or cylinder forstorage under pressure may be employed.

These cylinders have proven particularly convenient and advantageous toready use as a source of fluorine in the fluorinating of hydrocarbonsand the preparation of fluorides of uranlum. It will be understood thatvariations may be made in theapparatus described without departing fromthe scope of the present invention; for example, the tank or receptaclemay have any number of varied forms or shapes, may be different sizes,the walls may be of any suitable thickness, or the tank may be made insections with various types of control valves or traps, so the inventionis not to be limited to any particular arrangement or design, but onlyto the following claims.

We claim:

1. A fluorine gas storage vessel including a storage space defined by ametal of the group consisting of nickel, copper and an alloy of nickeland copper containing in excess of 60 per cent copper, and a, continuousadherent coating on the inner surface of said metal composed of a stablefluoride of said metal, said metal fluoride coating being impenetrableand non-reactive to fluorine gas.

2. A fluorine gas storage vessel including a storage space defined by acontinuous surface composed of nickel, and a continuous adherent coatingon said inner nickel surface composed of a stable fluoride of saidnickel, said nickel fluoride coating being impenetrable and non-reactiveto fluorine gas.

3. A fluorine gas storage vessel including a storage space defined by acontinuous surface composed of pper. and a continuous adherent coatingon said inner copper surface composed of a stable fluoride of saidcopper, said copper fluoride coating being impenetrable and non-reactiveto fluorine gas.

HOMER F. PRIEST.

ARIS'I'ID V. GROSSE.

REFERENCES CITED The following references are of record in the tile oithis patent:

UNITED STATES PATENTS Number Name Date 2,226,472 Jenness Dec. 24, 19401,826,236 Behan Oct. 6, 1931 1,771,638 Johnson July 29, 1930 2,293,266Mitchell Aug. 18, 1942 1,553,321 Meiklejohn Sept. 25, 1925 OTHERREFERENCES The Chemical Resistance of Engineering Materials" by Hamlinand Turner, pa e 153, published by the Chemical Catalog Co., of New Yorkcity, 1923.

The Handling of Corrosive Gases" by Chilton and Huey, Industrial andEngineering Chemistry, vol.224, No. 2, pages 125.429, inclusive,February 193

